1. Field of the Invention
The present invention relates to ocean going ships such as tankers, and more particularly to ships having a double or other hull configuration designed to reduce the likelihood of penetration of the hull and spillage of the contents of the ship in the event that the hull strikes an object, such as may result from a collision or from striking an underwater object such as a reef.
2. History of the Prior Art
It is known to provide ocean going ships such as tankers with a special hull configuration to resist penetration of the hull. In the event that the ship inadvertently strikes an underwater object such as a reef or a rock, the presence of an outer hull spaced from an inner hull reduces the chances of penetration of the inner hull and spillage of the ship's contents. Such hull configurations also provide protection in the event of collisions or other types of impacts by objects. Double hull configurations are becoming more and more commonplace, with increasing environmental concerns over the spillage of oil or other potential pollutants into the water.
In a typical double hull configuration for an ocean going ship, an outer hull surrounds and is spaced apart from an inner hull, with a plurality of unidirectional webs or other conventional bidirectional structural members extending between and coupling the two hulls together. Typically, longitudinal, and sometimes transverse, webs are disposed between the inner and outer hulls. The webs are active structural strength members which serve to join and hold the inner and outer hulls in the desired spaced-apart relation. Unfortunately, such active structural strength members are typically incapable of absorbing much energy in the event that the outer hull strikes an object. Consequently, both hulls must typically be of relatively thick construction and well separated.
It is also known in the art to provide a variety of different energy absorbing structural configurations and structural strength devices for use with ships and other watercraft of various designs. Unfortunately, such energy absorbing configurations and devices, which also form active structural strength members, have heretofore been incorporated into hull configurations with limited success. This is due to the inherent inability of the active structural strength members to absorb sufficient amounts of impact energy.
Examples of prior art in this area of structurally active hull configurations include U.S. Pat. Nos. 4,233,921 of Torroja et al., 4,227,272 of Masters, 4,254,727 of Moeller, 4,548,154 of Murata et al., 5,189,975 of Zednik et al., 4,128,070 of Shadid et al., and 3,157,147 of Ludwig, as well as Soviet Union Patent No. 1043-065-A and Japanese Patent No. 57-26075.
Thus, while various structurally active energy and shock absorbing devices have been proposed for use with ships and various watercraft in General, it has heretofore been unknown to provide a hull configuration with impact or energy absorbing means of sufficient effectiveness. Such means should not be structurally active, so as to be capable of functioning in a highly effective manner to absorb impact energy. It would therefore be advantageous to provide an energy absorbing double hull configuration for a ship capable of absorbing impacts and other energy imparted to the outer hull in a highly efficient and effective manner while preventing damage to or penetration of the inner hull. Such configuration should be nonstructurally active in order to be crushable, and therefore highly energy absorbing, and would permit relatively closer disposition of the outer hull to the inner hull, too. Close disposition of the inner and outer hulls also reduces the loss of useful cargo capacity. At the same time, such a configuration should permit both hulls to be of relatively thinner scantlings than in its absence.